Fatty acid compounds for use as drying oils



United States Patent e ice `assess?! iFATTY ACIDCOMPOUNDS IFORUSE AS DRYWNG @ILS V`Herman *S. Bloch, Skokie, .'Ill. assigner, Iby mesne assignments, to 'Universal VOil Products Company, Des Plaines., 111 a corporation of `Delaware "isoform-ing. .rind oet. s, 1955,;seeo10. :533,:117

screams. omiso-407) rlhis invention relates [to .a Lprocess .for .treating [fatty ,aacid compounds, .and ,particularly fatty .acid ,glyceidea ,for increasing .unsaturation .between `the .carbon bonds in .said compounds .and/or -or ,isomerizing `the unsaturated linkages ,insuch :compounds to .a .more highly conjugated system ;of .ethylenic bonds. .More speccalbs -thepresent each other.

Gne object ,of .the .invention .is .to .enhance .the .airtdrying Iproperties .of unsaturated .fatty ,acid compounds. .Still another .object .olf .the .invention .is to Yimprove :the chemical .reactivity `.of .the .present .fatty acid compounds and .thereby enhance their value as starting .materials in .the production of derivatives thereof and -to convert fatty .acid compounds having inferior properties of little or no utility to superiorrproducts .which vmaybe readily utilized in various Ysynthesesand Vfor various .commercial uses.

In one .of its embodiments the present invention relates to a process for isomeriz'ing a fatty acid compound to a product having a .conjugated system .of unsaturated 'linkages which comprises contacting said 'fatty acid compound at an elevated temperature with an alkaline metal .addition complex of an organic compound in which the metal vis bonded jto the organic compound through ,a metal-carbon atom linkage A more specific embodiment of the inventionconcerns '.the isomerization of 'linseed oil to a product 'having enhanced drying lprop erties'in which 'the unsaturatedllirik- 'ages have a more 'highly conjugated relationship with '.-respect :.to .each other by contacting vs-aid linseed o'l with 'an alkali metallhydroczarbon addition complex a't a itemperature of 'from about 100 to about 300 C., `at a pressure suicient to vmaintain .the Vreaction mixture in substantially liquid phase and for a time suicient to y'e'iect such isomerization,

Amore-specific embodiment :of the invention concerns :the 4tlehydroisomerization of soybean oil ywhereby arproduct havinglenhanced vdryingpropertiesiisiformed, in which `=process saidfsoybeanoilis contacted at -a temperature of from Vabout 160 to Aabout 300' C. with a mixture Yof a sodium-alkyl catalyst -and a vpromoter consisting of anthracene, lutilizing an :inert lgaseous atmosphere, at a pressure -suiiicient to maintain the Areaction mixture in substantially liquid phase.

It is welllknown that many fatty facid -ester oils of tnaturlly occurring Iorigin 'have -widely different vdrying fpropertieswhen fexposed :to atmospheric oxygen. IThus, many-oilsfsuch as soybean oil Iand sunoweroil dry :very 'olow'lyfiif'at all, Vwhen-exposed -to atmospheric vdrying -con- -ditions land `are thereforegenerally considered `non-drying or4 semi-drying oils, although they exist in abundance `and 1wou`ld `normally ind wide usage :if ithey possessed "-better .drying tqua-lities and rgreater /ohem'ical reactivity. l Other naturally occurring oils of the fatty acid glyoeride' .cluding suchoils `as 'tung oil 'and oitic'ica o'il. In many "inn .stances the 'fatty acids and certain fatty acid derivatives, such -as'the vesters o'f the lower molecular weightlalcoho'ls of monohydric, dhydric and trihydric classes 'and Athe amide derivatives would A"be of 4considerably greater *economic importancewere `a `method 'available Ifor con- 'verting vsuc'h fatty acid -compounds into Vmore highly unsaturated derivatives thereof and `.particularly derivatives `in which the unsaturation l'is of the conjugated `variety. The 'present jinvention is primarily concerned with Athe conversion o'f 'fattyfacidsffatty 'acid salts, fatty acid esters 'and Jfatty lacid amides into *their more Ahighly unsaturated derivatives and particularly such derivatives -in whichthe *unsaturated linkages 'become arranged 4in conjugated Tellations'liip'to each other. VThe means herein provided for effecting such conversion comprises contacting the fatty Aacid -compound Avwith an alkaline vearth -or alkali "metalhydrocarbon vaddi-tion vcomplex at reaction conditions Iwhich Aeifeet lthe #isomerization and/or 4dehydroisomerization lot" the lfatty acid compound to aproductfcontaining 'a greater -nurriber ofiunsaturated linkages and/or la prod- -uct in which Athe unsaturated linkages are in conjugated relationship with'each other. uln certain instances, it has Ebeenfountl desirabletoincorporate intothereactionmixture an -oxjganic compound *hereinafter more vspecifically characterized, havinga promoting -e'lect -on the -isomeriza- *tion and/or fde'hydroisomerization reaction, in order "to Vrials, it Ymay be vpreferred incertain cases to xutilize lother alcohol esters of the ffatty lacid portion -of the oil, 'for example, the :esters formed by yreplacing the glyceride esterlinkage with other rnonolorjpolyhydric alcohols, --if desired. Thus, the naturally 'occurring oils may ibe Ehydrolyzed to ree --thefatty acid -and the separated acid Vesterfified `with such -a'lcoho'ls Ias methanol, ethanol, 2isoipropanol, fazpolyhydroxy alcohol "such as yethyleneglycol, pentaerythritol, -sorbitol and -the ylike oran alkanolarnine represented, fior example, by the monoand poly- Lerhano'lam'inm. Instead o'f yesteriiyingthese =released fatty ,aeids, Ithey may also be .reacted with certain-alkaline bases, rsuch :as sodium, 4potassium -or l'lithium hydroxide, lcalcium, magnesium or barium hydroxide, their car ibonates, rbicarbonates 'or yweak 'acid salts or with other metal hydroxidesto'orm thetcorrespondingsoapsand the :latter utilized in 'the present process as charging vstock. These V:soaps :may also be 1prepared by Vdirect hydrolysis :and :neutralization Aof'theffatty Aacid yglyeeride, forming a .soap .in situ. ".Incertain other instances fthe amide-deriva- 't-iyes :of fthe ffatty acids may lbe ythe 4Jpreferred starting .materials in "the present process,` including lthe fatty yacids amides 'of ammonia and such amines las methylamine or dimethylamine, monoor YAdiethyla-mine la -pol-yamine, such as ethylene diamine, ldiethylene vtriamine, tri- 'ethylene `'tetra-amine, an varomatic `airline such asaniine or other amide products formed by dehydration of the fatty acid amine salt.

Typical fatty acid oils which illustrate the type of fatty acid glycerides utilizable in the present process are such drying and semi-drying types as linseed oil (either raw or boiled linseed oil), castor oil yor dehydrated castor oil,

y perilla oil, olive oil, peanut oil, Walnut oil, cottonseed oil,

cocoanut oil, soybean oil, hempseed oil, poppyseed oil, saillower oil, sunflower seed oil, whale oil, menhaden oil,

lard, tallow and other well-known fatty acid glycerides.

The fatty acids, when preferred herein, may be prepared from the naturally occurring oil by hydrolyzing the oil, for example by caustic, followed by acidification of the resulting soap and recovery of the released fatty acid. Although it is generally preferred to employ fatty acid compounds initially containing at least 1 double bond per molecule, great economic advantages may be obtained in dehydroisomerizing a normally saturated or only partly unsaturated fatty acid compound in order to convert a material having little initial value as a drying oil into a product of substantially greater drying properties by the present dehydroisomerizing process in which unsaturated bonds in conjugated relationship may be introduced into the compound and the resulting product thereby enhanced in value. Still another class of materials utilizable as the initial charging stock may be the oil-modified alkyd resins,

. oil-modified phenolic, or other drying oil-modified resinous materials prepared in la preceding synthesis.

The isomerization and dehydroisomerization reactions, herein referred to generically as isomerization processes are effected in accordance with the present invention by contacting the above-indicated starting material with an alkaline earth or alkali metal-addition complex of certain organic compounds which combine with the 'alkaline earth or alkali metal through a metal-carbon atom Ibond to form an active isomerization or dehydroisomerization catalyst, the particular resulting reaction depending upon the temperature and other conditions maintained during the conversion. These catalysts are usually prepared prior to the isomerization process of this invention within the reaction vessel in which the isomerization is eifected by combining an alkali metal such as sodium, potassium, lithium, rubidium and cesium or an alkaline earth metal, such as beryllium, magnesium, calcium, strontium or barium with an organic compound and particularly a hydrocarbon compound containing an active hydrogen atom on one of the carbon atoms of the compound which reacts with the metal to form a metal-carbon atom bond. Such hydrocarbons include the branched chain aliphatic hydrocarbons, such as isopentane, 2,3-dimethylbutane, 2,4-dimethylpentane, 2,2,3 trimethylbutane, 2,3,4 trimethylpentane and other homologous hydrocarbons containing up to about l2 carbon atoms per molecule. Other hydrocarbons suitable for forming the alkaline earth or alkali metal-hydrocarbon addition complexes are the aromatic hydrocarbons, including benzene, toluene, xylene, mesitylene, cumene, naphthalene, anthracene, uorene, tetralin, dihydronaphthalene, dihydroanthracene, -phenanthrene and their halogen-substituted derivatives such as chlorobenzene, o-chlorotoluene, p-bromoxylene, o-chloropropylbenzene, etc.; the alkyl-substituted and particularly methyl-substituted derivatives of the above such as dimethyl naphthalene, mono, di, and triphenyl methane; and hydrocarbons containing an acetylenic linkage, such as acetylene itself, propyne, ethylacetylene, pentyne, hexyne, heptyne, and higher homologs. Of the above, it is generally preferred to utilize the sodium and potassium-hydrocarbon addition complexes and of these, the complexes thereof with aromatic hydrocarbons such as naphthalene, toluene, cumene and the complex thereof with acetylene are generally preferred because of their high order of effectiveness in accomplishing the desired isomerization and dehydroisomerization reactions herein provided. The catalyst comprising the alkaline metal- Vhydrocarbon addition complexes may be charged individually into the reaction mixture as the complex itself or separately to form 4the `alkaline lmetal-hydrocarbon addition complex in situ during the ensuing reaction, or the catalyst complex as such may -be deposited upon or supported by an inert refractory substance, preferably selected from the refractory metal oxides, such as alumina, silica, magnesia, or upon other types o-f supporting materials such a's coke, charcoal, pumice, quartz, iron turnings, copper shot, ceramic saddles, etc.

The isomerization and dehydroisomerization reactions of the present invention are promoted by the addition of a small amount of a compound which is capable of forming a free radical in the presence of the catalyst and reactants and during the course of the isomerization reaction. These compounds, referred to herein as promoters by virtue of their catalyzing properties in either increasing the yield of isomerized product or in increasing the rate of the isomerization reaction combine with the alkaline metal to form a carbon-metal bond. Compounds of this character include heterocyclic compounds containing nitrogen in the nucleus of the ring such as pyridine, picoline, quinoline, isoquinoline, pyrrole, piperidine, yand their nuclearly alkylated derivatives; organic peroxide compounds such as acetyl peroxide, benzoyl peroxide,rdit butyl peroxide, t-butyl hydroperoxide, 4tetraline hydroperoxide, methylcyclopentyl hydroperoxide, dimethylcyclopentyl hydroperoxide, cumene hydroperoxide and others. Other organic-metallo compounds in which the organic radical is attached to the metal through a carbonmetal bond may also be utilized as promoters in the present process, including such compounds as the lead tetraalkyls, such 4as tetra-ethyl lead, a lead tetra-aryl, a lead alkylaryl, a zinc aryl, certain mercury dialkyls and diaryls, tin tetra-alkyls, and other organometallic compounds.

The amount of alkaline metal (i.e., alkaline earth or alkali metal) required and the amount of organic promoter preferred for use in the isomerization reaction are dependent upon the reaction conditions and upon the particular fatty acid compound charged to the process. In general, an excess of the alkaline metal over the organic compound capable of forming the organometallic complex utilized as the catalyst is employed inthe reaction, thereby ensuring the presence of free metal in the reaction zone, above that required to form the organometallic complex and to provide from 0.1 to about 20% vby weight thereof based on the fatty acid compound charged to the reaction zone, the ultimate proportion required -in many particular instances depending upon the depth of the dehydroisomerization of the charging stock desired. Since the catalyst is substantially unaltered during lthe course of the process, the catalyst may be recovered from the reaction products and recycled, if desired, in a succeeding reaction Iwith additional charging stock.

The process of this invention may be carried out in any suitable manner, including batch or continuous methods of operation, in an autoclave or a reaction vessel constructed of tubes through which the reactants are continuously charged, the latter being constructed either of steel or in the form of a glass-lined steel reactor. The process is carried out by charging the fatty acid compound in admixture with the alkaline metal-hydrocarbon complex to which mixture the promoter is added, if desired, into the reaction zone maintained at a temperature of from about to about 300 C., preferably at a temperature of from about to about 275 C., sucient pressure being applied to the reaction mixture to maintain the reactants in substantially liquid phase condition. Although not necessarily required, inert gas may be charged into the reactor to obtain the desired pressure which may range from atmospheric to 50 atmospheres, or more, in order to provide the above preferred liquid phase conditions. Such insert gases as nitrogen, carbon dioxide, methane, ethane, etc. also provide a blanket of inert atmosphere above the reactants to exclude oxygen from the system.

"promoter vislplaced iin the `reactor twhic'h preferably .f

equipped with a suitable zmixng :device tto maintain :the catalyst, promoter and fatty acid compound in intimate contact 'witheah-other-'during thefreacfion "The mixture of reaction products, .catalyst :and promoter, following the `completion of the isomerization reaction, is .thereafter subjected -to a 'suitable' separation procedure, las Vfor ex- `ample, decantation or nfiltration, to wrecover unconsuined lcatalyst, Lfollowed -by fractional 4distillation of the iorganic product to separate the promoter from the desired isomerized fatty acid compound. As indicated previously, the catalyst thus separated may be recycled, if desired, to the isomerization reactor for repeated reuse therein.

It has been found that the isomerization of the fatty acid compound involving a shift in the position of the unsaturated linkages present in the charging stock to conjugated positions occurs at relatively lower temperatures within the temperature range above specified, generally at temperatures within the range of from about 100 to about 250 C. and with smaller amounts of catalyst and promoter than is required to effect dehydroisomerization of the fatty acid compound, the latter reaction in which more highly unsaturated fatty acid compounds are produced generally occurring at temperatures within the range of from about 150 to about 300 C. For the latter dehydroisomerization type of reaction, catalyst to charging stock ratios sufficient to provide from about 5% to about 20% of the alkaline metal in the reaction mixture, based upon the fatty acid compound charged, are preferably employed. It has also been found that the residence time of the catalyst within the reaction mixture, which, in general, may be vwithin the range of from about one-half to about 6 hours, is usually greater for effecting dehydroisomerization than isomerization of the charging stock. In continuous types of operation, the residence time is measured as the average length of time the charging stock is within the reaction zone, maintained at the above temperature and pressure conditions, in contact with the catalyst. For the isomerization type of reaction, the residence time or period of contact between the charging stock and catalyst may be from about onehalf to about 3 hours, while dehydroisomerization is preferably effected over a reaction period of from about 2 to about 6 hours, more or less, depending upon the degree of saturation of the charging stock and the degree of unsaturation desired in the product.

Following completion of the isomerization or dehydroisomerization reaction the product is separated from the catalyst, usually by merely decanting the liquid product from the solid catalyst phase, thereafter washed with water to remove any dissolved or suspended catalyst and distilled, if necessary, to remove the promoter compound, if initially charged to the reaction mixture.

The present invention is further illustrated with respect to specific embodiments thereof in the following examples which, however, are not intended to limit the scope of the invention necessarily in accordance therewith.

Example I A sample of linseed oil which normally dries at a relatively slow rate upon exposure to atmospheric oxygen to form a relatively soft, abrasion-responsive film, is converted by isomerization to a product which dries at the same drying conditions at a higher rate of speed and which produces, when dried, a harder, tougher dried film than the starting material in accordance with the process of the present invention by means of the following procedure.

20 weight proportions of sodium and 50 weight proportions of anthracene, previously dried by distillation, are mixd'fin a stirred reactor at 100 C. for 1/2 hour to form -a sodium-anthracene complex :which fexists zin tthe 4form lof fa semi-'solid tform when cooled "tTo tthe abone ecom- 4p'lex 4is added 1000 weight proportions :of a :previously dried linseed oil having Van liodine member of :120iand ga imale'ic:anhydride Nalueof, .theflinsecd :oilbe'ingfadded at room temperature. The autoclave kiis ithen ushed iwith `lnitrogen, :thereafter Isealed and tthen :charged with v.nitrogen to 100 atmospheres pressure. 'The rautoclave is ithen :stirred by means of ra rapidly lrotating stirring pedal mounted :on fthe inside ,of ithe autoclave :as tlatter iis `heated :to a .temperature of 1275 LC. for '-3 Shouts, atollowed by fcooling 1to froom temperature. 'The iisomerized linseed oil product is decanted from the solid phase within .the reactor and heated to 200 C. at 0.5 mm. Hg pressure to distill over a major proportion-.of the dissolved anthracene. The recovered oil when tested for its drying properties by painting a thin film of the oil on a series of sheet aluminum test panels and after exposure to air at room temperature dries to a tack-free condition in approximately 110 hours and to a dried, hard film having a Sward hardness of 10 in approximately 1.5 days. The isomerized product has an iodine number of 197 and a maleic anhydride value of 20.

Example II In the following run a sample of sunflower seed oil which has an iodine number of 130 and a maleic anhydride value of 8 is subjected to dehydroisomerization in accordance with the procedure described as follows:

This oil in its unmodified state, is substantially inert to atmospheric oxygen, a thin film ofthe oil sprayed on an aluminum test panel and exposed to air at room temperature remaining undried at the test conditions, even after exposure to the atmosphere over a period of 20 days.

The catalyst in the following run is sodium acetylide prepared by mixing in an autoclave 50 grams of metallic sodium in liquid ammonia and reacting the latter at al temperature of 50 C. with one equivalent of acetylene charged into the reactor at a pressure slightly in excess of 20 atmospheres. The reaction is assisted by stirring the liquid ammonia suspension of sodium with a high speed stirring paddle. The resulting sodium-acetylene addition product is a white solid after evaporation of the liquefied ammonia. To the resulting catalyst is added 1000 weight proportions of sunflower oil having the above drying characteristics, followed by flushing the system with nitrogen and charging nitrogen into the reactor to a pressure of 100 atmospheres. The contents of the reactor are thereafter stirred as the mixture is heated to a temperature of 300 C. for 6 hours. The reactor contents are then separated by decanting the liquid product from the solid catalyst and the recovered converted sunflower seed oil heated to drive of any dissolved acetylene. The recovered oil has an iodine number of 180, a maleic anhydride value of 22 and when tested for its drying properties by exposing a thin film of the oil on an aluminum test panel to air at room temperature it produces a tackconsisting of an acetylenic hydrocarbon and anthracene.

2. A process for improving the drying properties of glyceride oils which comprises heating the glyceride oil to a tempera-ture of from about to about 300 C. in the presence of an alkaline metal addition complex having a metal-carbon atom bond and in which the alkaline metal is complexed with an acetylenic hydrocarbon.

3. A process for improving `the drying properties of glyceride oils which comprises heating the glyceride Oil to a temperature of from about 100 to about 300 C. in the presence of an alkaline metal addition complex having a metal-carbon atom bond and in which the alkaline metal is complexed with anthracene.

4. The process of claim 1 further characterized in that said glyceride oil is linseed oil.

5. The process of claim 1 further characterized in that said glyceride oil is sunflower oil.

6. The process of claim 1 further characterized in that the metal of said addition complex is sodium.

7. The process of claim 1 further characterized in that the alkali metal is complexed with an acetylenic hydrocarbon.

5 a temperature of from about 100 to about 300 C. in the presence of a sodium-anthracene complex.

References Cited in the le of this patent UNITED STATES PATENTS 2,242,230 Burr May 20, 1941 2,653,956 Marhofer et al Sept. 29, 1953 2,740,820 Wilson et al. Apr. 3, 1956 

1. A PROCESS FOR IMPROVING THE DRYING PROPERTIES OF GLYERIDE OILS WHICH COMPRISES HEATING THE GLYCERIDE OIL TO A. TEMPERATURE OF FROM ABOUT 100* TO ABOUT 300*C. IN THE PRESENCE OF AN ALKALINE METAL ADDITION COMPLEX HAVING A METAL-CARBON ATOM BOND AND IN WHICH THE ALKALINE METAL IS COMPLEXED WITH A HYDROCARBON SELECTED FROM THE GROUP CONSISTING OF AN ACETYLENIC HYDROPCARBON AND ANTHRACENE. 